Bought a new 4TB disk for my gaming rig, pulled out the old 1TB one and plugged it back on my old machine. Installed Ubuntu Server. Instalation went well after I figured I needed the IOMMU turned on.

Later went to play some BfA on the gaming rig and... No boot disk recognized. Ahn?
My SSD is plugged in. SATA cable is well seated. Thing was working not 30min before...

After a loooong time trying to figure out if it was hardware or micro$hit's Windows 10, I finally figured it:
It seems Windows installed its EFI partition on the old HDD. So my SSD is basically a single, large NTFS volume. Now I need to download the Win10 ISO, boot up the install disk and use the cmd prompt to create a new EFI partition on my SSD. Ugh.

Fucking Windows didn't think to install its boot manager on its own disk. "Nah, just gonna use this random magnetic disk here". Why? My login queues are already huge on WoW, why must this wankstain of an OS annoy me even more?